JAPton blog

[Lutin]

More grinding...
Progress:

That's a big old chunked that's been removed. You're a braver man than me.

Top thread by the way. Especially for all us armchair bike fettlers.

[Rockburner]

More grinding...
Progress:

That's a big old chunked that's been removed. You're a braver man than me.

Top thread by the way. Especially for all us armchair bike fettlers.

yeah - it looks like a big chunk..... and yes - I DID think ... "err wtf".... when I was done!

In reality I reckon it's less than 1% of the overall mass of the assembly, it's fucking heavy. (actually - I'll weight it next time!)

[Skub]

It's a fine line when you get into something. Periodically I find my self rushing to do stuff and need to stop and ask myself why. The real pleasure in spannering is workng without time constraints and despite knowing this,I still have to remind myself to take a fackin breath!

[Dodgy69]

I'll be glad when it's all done, don't know about your RB.

[Rockburner]

So - yesterday I got the opportunity to dive into the workshop...

4 hours of facking about later....

In imperial...


and metric units:


9.3 kilos.... yeah - that's pretty hefty.

I pushed some oil through the big end to clear it out before proceeding:



Then left it to drain for a few minutes


Before starting the iterative process of finding the best mix of shims for an acceptable end-float and conrod centering:

Each trio of photos will be: the measured overall end-float, then conrod vs case centre-line with crank to LEFT, then crank to RIGHT.
one:




two:




three:




four:




six, no five! :

(fecking guage)




That's acceptable and seemed to be as close as I was going to get with the shims I have. Between 0.015 and 0.020 overall end float, and the conrod (allowing for the big-end float as well) is as centred as I can get it.

A sure sign of a troubled mind.....


I've ended up with a very thin shim on one side, and quite a thick combo on the other.

I believe the main reason for this is that the main bearing liners are of different vintages, and protrude into the cases by different amounts (which is the main reason for the adjustable shimming). The old liner in the Timing side case is only slightly proud of the case it fits into (which is the side of the crank-wheel I had to grind down). The new liner I fitted into the output side is much more proud of the case: ie, it has a thicker "brim" (think of it shaped like a top hat); so, to center the conrod, there is less "room" on the output side between the liner and the wheel.

I think I spent about 3 hours on that: each measurement above represents unbolting the cases, pulling out the wheels, pondering the next combo, then reassembling (making sure not to fling bearing pins everywhere), bolting up and resetting the guage. The guage was a bugger to zero each time.

I then restarted the assembly process:
First get the mating faces clean:

Can you get high on meths fumes??


Stick the wheels in with the bearings and shims, then fetch the sealant.


Oh FFS!


Even with having squooged the stuff up and down the tube to try to get it mixed a bit better.. (metal tube - hence the leak above) it still came out very runny. In fact, it literally poured out of the tube (which is why I ended up with slightly more on there than I had planned. )




I cleaned it all up as best I could before it got too sticky




It does make quite a mess....


I can only hope that there isn't too much dribble inside the cases themselves.

Just for shits and giggles I checked the end-float again:

(fecking guage)


Satisfied with that, the end-float is still as I hoped and with luck, the 3Bond will go off properly.

I decided to carry on and fitted the piston again: naturally I scratched hell out of the piston getting the sodding gudgeon pin circlips in:




Then fitted the barrel rods:



To get a good "heft" on the barrel rod nuts I put the whole thing into the vice briefly:


So - we're back on track, if behind schedule slightly...


I left it there for the evening to let the 3Bond go off, and to ponder the next move:
Specifically: do I try the 3Bond on the base gasket again... or use something else: the immediately available options are Hylomar Blue, or silicon RTV. I'm tempted to try the RTV to be frank, mainly because (from memory of last time I used it), it's much, much less runny than the 3Bond, and so easier to be exacting about where it's applied. I don't really want too much of it dribbling into the cases.

So, I went back in and fed the cat:

[Buckaroo]

So - yesterday I got the opportunity to dive into the workshop...

4 hours of facking about later....

In imperial...


and metric units:


9.3 kilos.... yeah - that's pretty hefty.

I pushed some oil through the big end to clear it out before proceeding:



Then left it to drain for a few minutes


Before starting the iterative process of finding the best mix of shims for an acceptable end-float and conrod centering:

Each trio of photos will be: the measured overall end-float, then conrod vs case centre-line with crank to LEFT, then crank to RIGHT.
one:




two:




three:




four:




six, no five! :

(fecking guage)




That's acceptable and seemed to be as close as I was going to get with the shims I have. Between 0.015 and 0.020 overall end float, and the conrod (allowing for the big-end float as well) is as centred as I can get it.

A sure sign of a troubled mind.....


I've ended up with a very thin shim on one side, and quite a thick combo on the other.

I believe the main reason for this is that the main bearing liners are of different vintages, and protrude into the cases by different amounts (which is the main reason for the adjustable shimming). The old liner in the Timing side case is only slightly proud of the case it fits into (which is the side of the crank-wheel I had to grind down). The new liner I fitted into the output side is much more proud of the case: ie, it has a thicker "brim" (think of it shaped like a top hat); so, to center the conrod, there is less "room" on the output side between the liner and the wheel.

I think I spent about 3 hours on that: each measurement above represents unbolting the cases, pulling out the wheels, pondering the next combo, then reassembling (making sure not to fling bearing pins everywhere), bolting up and resetting the guage. The guage was a bugger to zero each time.

I then restarted the assembly process:
First get the mating faces clean:

Can you get high on meths fumes??


Stick the wheels in with the bearings and shims, then fetch the sealant.


Oh FFS!


Even with having squooged the stuff up and down the tube to try to get it mixed a bit better.. (metal tube - hence the leak above) it still came out very runny. In fact, it literally poured out of the tube (which is why I ended up with slightly more on there than I had planned. )




I cleaned it all up as best I could before it got too sticky




It does make quite a mess....


I can only hope that there isn't too much dribble inside the cases themselves.

Just for shits and giggles I checked the end-float again:

(fecking guage)


Satisfied with that, the end-float is still as I hoped and with luck, the 3Bond will go off properly.

I decided to carry on and fitted the piston again: naturally I scratched hell out of the piston getting the sodding gudgeon pin circlips in:




Then fitted the barrel rods:



To get a good "heft" on the barrel rod nuts I put the whole thing into the vice briefly:


So - we're back on track, if behind schedule slightly...


I left it there for the evening to let the 3Bond go off, and to ponder the next move:
Specifically: do I try the 3Bond on the base gasket again... or use something else: the immediately available options are Hylomar Blue, or silicon RTV. I'm tempted to try the RTV to be frank, mainly because (from memory of last time I used it), it's much, much less runny than the 3Bond, and so easier to be exacting about where it's applied. I don't really want too much of it dribbling into the cases.

So, I went back in and fed the cat:

I'm keeping with the current theme: That's one giant step for RB, a giant leap for Japton. Keep it going!

[Zimbo]

Great thread. I help a mate out with his Classic 500 race car, 1953 Cooper 500, powered by the same motor, running on ethanol.

https://photos.app.goo.gl/ofQZvnhw2ZqHSw3n7

https://photos.app.goo.gl/n6cJpu1s8fFSWiJ87

[Rockburner]

Great thread. I help a mate out with his Classic 500 race car, 1953 Cooper 500, powered by the same motor, running on ethanol.

https://photos.app.goo.gl/ofQZvnhw2ZqHSw3n7

https://photos.app.goo.gl/n6cJpu1s8fFSWiJ87

Great stuff! A few of the features of my engine are from that world. One my Dad's friends who helped with the original build was an F500 racer.

I'm assuming that first photo is mid-re-fit of the engine?? The primary chain is a tad loose!

Does your mate do his own engine work or pass it on to someone else?

[Skub]

Your pussy is very like our visitor kat.

Ruby - Imgur (8).jpg (3.14 MiB) Viewed 1207 times

[Zimbo]

Picture was taken after the rear axle drive chain had broken in qualifying at the Silverstone Festival, you can see the rear chain is missing. It runs a Norton gearbox, the rear axle is fixed so you need to adjust the rear drive chain tension by moving the gearbox backwards or forwards, and then adjust the primary drive chain tension by moving the engine backwards or forwards. Interesting carb, two float chambers one either side to maintain fuel delivery under side loads when cornering. As it runs on Methanol it's not that easy to start from cold but OK when warm. It's been reliable apart from some magneto issues in the first season, engine work is done by a specialist if required, we have a spare engine as well. Cars in the class tend to either run the Jap 500 motor or Manx Norton motor.
https://photos.app.goo.gl/Y7rkfrCBbRw5A23Y8

[Rockburner]

Picture was taken after the rear axle drive chain had broken in qualifying at the Silverstone Festival, you can see the rear chain is missing. It runs a Norton gearbox, the rear axle is fixed so you need to adjust the rear drive chain tension by moving the gearbox backwards or forwards, and then adjust the primary drive chain tension by moving the engine backwards or forwards. Interesting carb, two float chambers one either side to maintain fuel delivery under side loads when cornering. As it runs on Methanol it's not that easy to start from cold but OK when warm. It's been reliable apart from some magneto issues in the first season, engine work is done by a specialist if required, we have a spare engine as well. Cars in the class tend to either run the Jap 500 motor or Manx Norton motor.
https://photos.app.goo.gl/Y7rkfrCBbRw5A23Y8

That'll be an Amal type 27 most likely... I've been looking for one but they're like hen's teeth (and fucking expensive when they do crop up). The main benefit of them is that they can flow a LOT of fuel into the main jet, which apparently is what the JAP engine likes, regardless of fuel type.

I spoke to an Amal specialist last time I was at Kempton and when I said I was using a Monobloc he said that that's most likely to be what was causing the issues I was having last year when the bike wouldn't run at WOT. Apparently the passage in the Monobloc that fuel goes through from the first chamber to the main jet is simply not large enough. In the past he'd modified Monoblocs for use on JAP engines, but recommended I try a Concentric instead, because they don't restrict the fuel flow in the same way. On a Concentric the main jet sits in the float chamber like a modern carb, and the line from the tank goes straight into that float chamber (obviously!)

I've got a Concentric, so will very likely try it once the engine is back together.

[Dodgy69]

At least you missed the cats tail when you dropped the bottle of bleach. Good thread BTW.

[Zimbo]

I'll get a few more pictures when we are next out

[Rockburner]

So - I got into the workshop for a lengthy session on Saturday... lots of photos!

First I turned the piston around... The gudgeon pins are getting a little easier, but they're still gits to get into place properly.

Then confirmed that the ring gaps were in the right places:




Fitted the ring clamp


Then I fed some oil into the output side main bearing, to make sure it has some. Mainly because I still don't really see how oil gets into that tiny hole... just from splashing up??


I'd decided to use the RTV for the base gasket this time. (Once I'd cleared the dried out stuff in the nozzle.)


It's a lot more controllable than the 3Bond.


I put a layer on the top of the gasket too, once I'd got it in place over the piston. I managed to not get too much goo in places it shouldn't be!


Cylinder back on. Wasn't too hard this time.


Prepped the head gasket again - both sides this time. Note to self... that mat is NOT fully heatproof... (I'm sure I took a picture of the somewhat heated newspaper the mat was sitting on...)


Before dunking it.


I wanted to redo the head gasket mainly because I'd only heated it up on one side previously and I didn't think it had "taken" properly.

Head gasket in place.



Once I'd spun the head rods up into the head I put the whole thing into the vice again to get things tight.


Fitted the timing wheel - mainly because it give me a decent grip for rotating the thing. (and marked a reminder....)


Stuck the tell-tale into the plug hole:


Fitted the lower valve covers.


Fitted the push rod guide fittings. (Only using the adjustable because they're rather large...)


Valve caps.


Fitted the rocker box


These two oil feed nuts are an absolute bastard to get tight because you can't get a spanner on them.
I eventually (more later) managed to get them as tight as possible, but they need to be loose AS you fit the box in order to get the pipes into the feed holes in the head that feed the valve guides. I may need to find a split spanner or something to get them done up properly. (I'm also tempted to replace them because they're completly knackered). I had the box on and off about 3 times trying to figure out how to fit the thing properly.


This is the point where I realised that the thread in the rocker box for the hole that holds the valve cover was fucked.


So the rocker box came off again!


I then spent quite a while trying to find larger screws that would be appropriate. I initially had the plan to drill out the hole to a larger diameter, then thread for a bigger screw.
After I'd started finding screws and had dug out some taps...
I realised that I should figure out what the original thread was...
It's a 1/4 BSF.
And I've got a thread repair kit for that!

So I dug it out, drilled the hole out and tapped it for the repair:




All good!


Still got plenty of inserts left, but hopefully I won't need many more!


I also shortened the bolt that was in use slightly (it's not a match with the rest of the bolts in use here)


Always round off the end...


And, even though I'd spun the nuts back off the bolt to clear the thread ends, I also span a die down the bolt too.


Now it's a matching length


Test fitting


So - time to start on this side of things....


Cam followers going in.


Timing pinion and cam-shaft into the chest.


Push rods in. Bit of a git to get in tbh, the exhaust especially, the camshaft has to come out to get the pushrod in between the rocker and follower.



aaaaand that's where Saturday's fun ended. I needed to do some reading to remind myself of the process for timing the valves. This is, again, where my existing knowledge is completely lacking, I've never done this before, but I'm very aware of the risks involved in getting it wrong!

[Rockburner]

Aaaand I got into the workshop today as well!

I spent some time reading Fenner, Pitman, Irving and Greenwood... and while they don't disagree with each other completely.... there are some differences.

But - we'll get to that.

Back in the workshop I double checked the current setup:

This note tells me how the timing pinion on the crank-shaft was fitted prior to dismantling:


And that's how I fitted it:


The books had said that one trick was to fit the mag-platform/timing chest cover to check the backlash and to ensure that the gears weren't jumping about.

So I fitted the studs: using the double-nut trick to get the studs themselves nice and tight:


Timing chest cover in place (but not pushed fully home)
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This is what I was getting as backlash with both valves open.




2 degrees of backlash. 1 degree is what is mentioned in the books, so that's something to talk to the guru about... along with other things, but I'm not distubing him on Easter weekend!



I carried on regardless - it's all good practise.
You can't really see it here.... but the push rods are ever so slightly not straight.... which means they should be replaced.



I played with the timing wheel and piston tell-tale until I got the 0 degree mark right at TDC.


The tappet clearance, according to one of the books should be 0.003" and 0.004", then reset to 0.002" once the timing is done: which seems a tad odd... but this comes from the Greenwood book - which is based, from my understanding, on racing experience.






Set both sides easily enough.

This is the timing numbers from the 4 books I've got....


I wanted to check the valve openings with the dial guages, so I dug out the ally bracketing I had found a few months ago and made a start on making up the 2 small brackets I needed.








Bit of heat to make the bend easier


Along with an assist from my number one, all time, favourite tool.


The holes for the small end are 1/4", and I ended up doing the other end 1/4" as well - turns out the dial guage lugs were exactly that size.


Guages fitted and aligned.



I lost count of how many times I spun this thing.
I marked the "correct" timings on the wheel in black, and the timings that I had, which were surprisingly close for a first go, in red. But I can't quite make sense of the offsets: I had expected that if they were "early" at one point, they'd be early all round.... but they're not... not quite... I am wondering if I've got a "sporty" cam here... but will be talking to the guru about it first.



One other thing I have seen a photo of, is a little handle on the timing wheel to make it easier to rotate, so I figured that might be worth adding.


I used an M5 bolt and a cork... It may get improve upon in the future!


So - I need to talk to the guru next week, and buy new push-rods, along with the ends (which come separate), a new oil-union for the rocker box, some new oil-nut fittings, a spanner to fit the buggers (if I can find the right one),

I have another job coming in which necessitated moving a few things about in the workshop... and while doing so I discovered that the right side fork is weeping oil... and there was oil under the gearbox, which I think "might" have been coming from the kickstart shaft. Goldarn it! GAH!

[Dodgy69]

Still a very engaging read.

[Rockburner]

Had a nice video call with the Guru yesterday, and learnt a few more useful things.

Like: when checking the backlash it's best to do this with the timing chest cover fitted and nipped up!
So - I did that, and:



I'd say that's as close to 1 degree as you're going to get!

The backlash between the timing pinion and camshaft is fine! We had a conversation about the various options for the timing pinion - they were made with allowances for the backlash (-6, standard, +6, +12, etc, he's seen a -20!) and mine is a -6. He initially recommended going up to a "standard" if I could find one, but after rechecking (properly!), it's all good, which is a bit of a relief because these things are just not made any more! If I was to find a 2nd hand one, I'd have no idea how worn it might be (which is the same issue with pretty much all the parts for these engines).

I'm also going to make sure that when I'm doing the valve-timing from now on I'm going to have the timing chest cover fitted and nipped up to ensure things don't have too much play: it makes more of a difference than I realised!


Obviously the guru does this so often, he actually has a cut-down cover with the timing pinion exposed so he can adjust it without removing the cover! Very handy, but massively overkill for me, once I've done this and got it as best I can, it won't be getting changed again. The ignition timing on the other hand....

The guru reminded me of something else: the "critical" valve timing to get right is the Inlet Opening position. Get that right and everything else will follow : the cams and cam-shaft and gear are all one solid piece, so if it's right in one place, it can't be "wrong" anywhere else, so I'll work off that principle.

We also discussed the bent push-rods, it's just something that happens - they're tubes, not solid. I need to find some replacements, and we discussed sources.
This is the worst one: Dial at 0

Dial showing the runout:


FYI: that's the crappy dial, I've discovered that the needle is a little loose and will wander over time. ffs. It's ok for one-off measurements though.

The other rod isn't as bad, but best to replace the pair while I'm here:




He told me that apparantly one of the main suppliers tried to sell ally push-rod tubes a while back, which wasn't a good idea as they all bent! The people who'd bought them were (understandably) pretty pissed off and complained bitterly, but he doesn't know if the company still sells them, or what they're made of: I shall investigate!

The current preferred material for race engines, running full power, is chro-moly tubing, but he reckons that I will be fine with regular steel tubing: I need to take the ends off my current rods (the ends are soldered on), and check the wall thickness, then go find some steel tubing of similar (or thicker) wall and see about making some up; well; presuming I can't find some ready made replacements somewhere else.

hey ho... do a job, make a job (as my ex used to say...)


Oh yeah - I also discovered last night that the classic bike track-day that I was sort of attempting to have the bike ready for has been moved to June or July, from May: so that "deadline" is no longer looming as heavily, phew. What with the discovery of the fork and gearbox leaks I was thinking it wasn't going to be ready, now I still have a vague chance if I still want to aim for it.

[Druid]

I have rebuilt a few engines in my time, from twin cam IL4s to bevel drive desmo Ducatis, but this looks to be more challenging than anything I've had to deal with. Well done for even attempting it, I'm really impressed with your work.

[Rockburner]

I have rebuilt a few engines in my time, from twin cam IL4s to bevel drive desmo Ducatis, but this looks to be more challenging than anything I've had to deal with. Well done for even attempting it, I'm really impressed with your work.

That's very kind of you to say! Tbh, for me, this stuff, while being new to me, is all pretty simple; for me: a bevel drive desmo would be waaaaay too complicated to work on! Getting bevels aligned right would be the stuff of nightmares for me! I've read the workshop manual for my shaft drive BMWs and setting up new bearings and shim for the final drive box is something I'm very happy to hand over to someone who knows what they're doing!

[ogri]

Saw a nice Japton on portsdown hill this morning, looked and sounded good.